package com.wenhao.newcode.huawei.medium2016;

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

/**
 * @author Wenhao Tong
 * @create 2021-07-21 13:40
 */
public class Main2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String str = scanner.next();
            Set<Character> set = new HashSet<>();
            String res = "";
            for (int i = 0;i < str.length();i++) {
                if (!set.contains(str.charAt(i))) {
                    set.add(str.charAt(i));
                    res += str.charAt(i);
                }
            }
            System.out.println(res);
        }
    }
}
